Celestite (SrSO₄) is strontium sulfate, isostructural with barite. Its name, from Latin “caelestis” (heavenly), references the iconic sky-blue color of the finest specimens — color that comes from natural radiation damage to its crystal lattice. Madagascar geode interiors lined with sky-blue tabular Celestite crystals are the world standard for the species, while Sicilian historical specimens preserve the type material.
Key Facts
- Mohs hardness 3–3.5 — soft, easily damaged.
- Specific gravity 3.96 — heavier than barite of similar appearance.
- Orthorhombic; isostructural with barite (BaSO₄) and anglesite (PbSO₄).
- Sky-blue coloration is the most prized; colorless, white, gray, yellow, and pink also occur.
- Common geode-filling mineral in sedimentary basins.
Notable Localities
Sakoany (Madagascar) is the world’s premier source for sky-blue tabular crystals. Sicily (Italy) is the type locality. Lake Erie geodes (Ohio, USA) produce classic American material.
Found at these Localities
- Lanping Pb-Zn-Cu Field (兰坪铅锌铜矿田)
- Italian Volcanic Province (Vesuvius / Lipari / Etna) (意大利火山矿物产地)
